The ergodic and non-ergodic phases in one dimensional clean Jaynes-Cummings-Hubbard system

TL;DR

This paper investigates the transition between ergodic and non-ergodic phases in a one-dimensional Jaynes-Cummings-Hubbard system, revealing phase boundaries, violations of thermalization, and links to phase transitions.

Contribution

It provides a detailed analysis of ergodic and non-ergodic phases, including the existence of non-ergodic phases in the thermodynamic limit and their relation to phase transitions.

Findings

Transition from ergodic to non-ergodic phases with large atom-photon detuning

Non-ergodic phases may persist in the thermodynamic limit

Non-ergodic phases violate the eigenstate thermalization hypothesis

Abstract

We study the ergodic and non-ergodic behaviors of a clean Jaynes-Cummings-Hubbard chain for different parameters based on the average level spacings and the generalized fractal dimensions of eigenstates by using exact diagonalization. It can be found that a transition from ergodicity to non-ergodicity phases happens when the atom-photon detuning is large, and the non-ergodic phases maybe exist in the thermodynamic limit. We also find that the non-ergodic phase violates the eigenstate thermalization hypothesis. Finally, we study the many-body multifractality of the ground state and find that the derivative of the generalized fractal dimensions can determine the critical point of the Superfluid-Mott-insulation phase transition in a small range of parameters under different boundary conditions and there is no ergodicity for the ground state.